Dell Inspiron 23 (2350, Mid 2013) - Manual (Page 102)

The display settings controls functions as describe below:
• Increase display brightness: Press to increase the display brightness.
• Decrease display brightness: Press to increase the display brightness.
• Display off: Press and hold to turn off the display.
• Input source select: Press and release to switch between video input
sources.
The display settings controls provide an on-screen display (OSD) when your
computer is connected to an external video output device.
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